Based on the mode of occurrence, gold is classified into three categories: microscopic gold, submicroscopic gold and surface-bound gold. Microscopic gold, or visible gold, refers to gold minerals in which Au occurs in a substantial amount, such as native gold and electrum. Submicroscopic gold, ie invisible gold, refers to gold contained in the structure of other minerals (mainly sulfides) in minor to trace amounts. Surface gold is the gold that was adsorbed onto the surface of other minerals during mineralisation and subsequent oxidation or metallurgical processing._x000D_
Gold mineralogy has a significant impact on its extractive metallurgy. Gold process mineralogy helps address problems related to gold ore processing. It is widely used as a predictive and troubleshooting tool in gold ore processing, and provides useful information on process selection, flow sheet development, recovery improvement and reagent consumption optimisation. This paper will begin with the classification of gold ores, and will focus on gold mineralogy and how it impacts extractive metallurgy through case studies.